br_forward.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *	Forwarding decision
  4 *	Linux ethernet bridge
  5 *
  6 *	Authors:
  7 *	Lennert Buytenhek		<buytenh@gnu.org>
  8 */
  9
 10#include <linux/err.h>
 11#include <linux/slab.h>
 12#include <linux/kernel.h>
 13#include <linux/netdevice.h>
 14#include <linux/netpoll.h>
 15#include <linux/skbuff.h>
 16#include <linux/if_vlan.h>
 17#include <linux/netfilter_bridge.h>
 18#include "br_private.h"
 19
 20/* Don't forward packets to originating port or forwarding disabled */
 21static inline int should_deliver(const struct net_bridge_port *p,
 22				 const struct sk_buff *skb)
 23{
 24	struct net_bridge_vlan_group *vg;
 25
 26	vg = nbp_vlan_group_rcu(p);
 27	return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
 28		(br_mst_is_enabled(p) || p->state == BR_STATE_FORWARDING) &&
 29		br_allowed_egress(vg, skb) && nbp_switchdev_allowed_egress(p, skb) &&
 30		!br_skb_isolated(p, skb);
 31}
 32
 33int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 34{
 35	skb_push(skb, ETH_HLEN);
 36	if (!is_skb_forwardable(skb->dev, skb))
 37		goto drop;
 38
 39	br_drop_fake_rtable(skb);
 40
 41	if (skb->ip_summed == CHECKSUM_PARTIAL &&
 42	    eth_type_vlan(skb->protocol)) {
 43		int depth;
 44
 45		if (!vlan_get_protocol_and_depth(skb, skb->protocol, &depth))
 46			goto drop;
 47
 48		skb_set_network_header(skb, depth);
 49	}
 50
 51	br_switchdev_frame_set_offload_fwd_mark(skb);
 52
 53	dev_queue_xmit(skb);
 54
 55	return 0;
 56
 57drop:
 58	kfree_skb(skb);
 59	return 0;
 60}
 61EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);
 62
 63int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 64{
 65	skb_clear_tstamp(skb);
 66	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
 67		       net, sk, skb, NULL, skb->dev,
 68		       br_dev_queue_push_xmit);
 69
 70}
 71EXPORT_SYMBOL_GPL(br_forward_finish);
 72
 73static void __br_forward(const struct net_bridge_port *to,
 74			 struct sk_buff *skb, bool local_orig)
 75{
 76	struct net_bridge_vlan_group *vg;
 77	struct net_device *indev;
 78	struct net *net;
 79	int br_hook;
 80
 81	/* Mark the skb for forwarding offload early so that br_handle_vlan()
 82	 * can know whether to pop the VLAN header on egress or keep it.
 83	 */
 84	nbp_switchdev_frame_mark_tx_fwd_offload(to, skb);
 85
 86	vg = nbp_vlan_group_rcu(to);
 87	skb = br_handle_vlan(to->br, to, vg, skb);
 88	if (!skb)
 89		return;
 90
 91	indev = skb->dev;
 92	skb->dev = to->dev;
 93	if (!local_orig) {
 94		if (skb_warn_if_lro(skb)) {
 95			kfree_skb(skb);
 96			return;
 97		}
 98		br_hook = NF_BR_FORWARD;
 99		skb_forward_csum(skb);
100		net = dev_net(indev);
101	} else {
102		if (unlikely(netpoll_tx_running(to->br->dev))) {
103			skb_push(skb, ETH_HLEN);
104			if (!is_skb_forwardable(skb->dev, skb))
105				kfree_skb(skb);
106			else
107				br_netpoll_send_skb(to, skb);
108			return;
109		}
110		br_hook = NF_BR_LOCAL_OUT;
111		net = dev_net(skb->dev);
112		indev = NULL;
113	}
114
115	NF_HOOK(NFPROTO_BRIDGE, br_hook,
116		net, NULL, skb, indev, skb->dev,
117		br_forward_finish);
118}
119
120static int deliver_clone(const struct net_bridge_port *prev,
121			 struct sk_buff *skb, bool local_orig)
122{
123	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
124
125	skb = skb_clone(skb, GFP_ATOMIC);
126	if (!skb) {
127		DEV_STATS_INC(dev, tx_dropped);
128		return -ENOMEM;
129	}
130
131	__br_forward(prev, skb, local_orig);
132	return 0;
133}
134
135/**
136 * br_forward - forward a packet to a specific port
137 * @to: destination port
138 * @skb: packet being forwarded
139 * @local_rcv: packet will be received locally after forwarding
140 * @local_orig: packet is locally originated
141 *
142 * Should be called with rcu_read_lock.
143 */
144void br_forward(const struct net_bridge_port *to,
145		struct sk_buff *skb, bool local_rcv, bool local_orig)
146{
147	if (unlikely(!to))
148		goto out;
149
150	/* redirect to backup link if the destination port is down */
151	if (rcu_access_pointer(to->backup_port) &&
152	    (!netif_carrier_ok(to->dev) || !netif_running(to->dev))) {
153		struct net_bridge_port *backup_port;
154
155		backup_port = rcu_dereference(to->backup_port);
156		if (unlikely(!backup_port))
157			goto out;
158		BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(to->backup_nhid);
159		to = backup_port;
160	}
161
162	if (should_deliver(to, skb)) {
163		if (local_rcv)
164			deliver_clone(to, skb, local_orig);
165		else
166			__br_forward(to, skb, local_orig);
167		return;
168	}
169
170out:
171	if (!local_rcv)
172		kfree_skb(skb);
173}
174EXPORT_SYMBOL_GPL(br_forward);
175
176static struct net_bridge_port *maybe_deliver(
177	struct net_bridge_port *prev, struct net_bridge_port *p,
178	struct sk_buff *skb, bool local_orig)
179{
180	u8 igmp_type = br_multicast_igmp_type(skb);
181	int err;
182
183	if (!should_deliver(p, skb))
184		return prev;
185
186	nbp_switchdev_frame_mark_tx_fwd_to_hwdom(p, skb);
187
188	if (!prev)
189		goto out;
190
191	err = deliver_clone(prev, skb, local_orig);
192	if (err)
193		return ERR_PTR(err);
194out:
195	br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);
196
197	return p;
198}
199
200/* called under rcu_read_lock */
201void br_flood(struct net_bridge *br, struct sk_buff *skb,
202	      enum br_pkt_type pkt_type, bool local_rcv, bool local_orig,
203	      u16 vid)
204{
205	enum skb_drop_reason reason = SKB_DROP_REASON_NO_TX_TARGET;
206	struct net_bridge_port *prev = NULL;
207	struct net_bridge_port *p;
208
209	br_tc_skb_miss_set(skb, pkt_type != BR_PKT_BROADCAST);
210
211	list_for_each_entry_rcu(p, &br->port_list, list) {
212		/* Do not flood unicast traffic to ports that turn it off, nor
213		 * other traffic if flood off, except for traffic we originate
214		 */
215		switch (pkt_type) {
216		case BR_PKT_UNICAST:
217			if (!(p->flags & BR_FLOOD))
218				continue;
219			break;
220		case BR_PKT_MULTICAST:
221			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
222				continue;
223			break;
224		case BR_PKT_BROADCAST:
225			if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
226				continue;
227			break;
228		}
229
230		/* Do not flood to ports that enable proxy ARP */
231		if (p->flags & BR_PROXYARP)
232			continue;
233		if (BR_INPUT_SKB_CB(skb)->proxyarp_replied &&
234		    ((p->flags & BR_PROXYARP_WIFI) ||
235		     br_is_neigh_suppress_enabled(p, vid)))
236			continue;
237
238		prev = maybe_deliver(prev, p, skb, local_orig);
239		if (IS_ERR(prev)) {
240			reason = PTR_ERR(prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
241				 SKB_DROP_REASON_NOT_SPECIFIED;
242			goto out;
243		}
244	}
245
246	if (!prev)
247		goto out;
248
249	if (local_rcv)
250		deliver_clone(prev, skb, local_orig);
251	else
252		__br_forward(prev, skb, local_orig);
253	return;
254
255out:
256	if (!local_rcv)
257		kfree_skb_reason(skb, reason);
258}
259
260#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
261static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
262			       const unsigned char *addr, bool local_orig)
263{
264	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
265	const unsigned char *src = eth_hdr(skb)->h_source;
266	struct sk_buff *nskb;
267
268	if (!should_deliver(p, skb))
269		return;
270
271	/* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
272	if (skb->dev == p->dev && ether_addr_equal(src, addr))
273		return;
274
275	__skb_push(skb, ETH_HLEN);
276	nskb = pskb_copy(skb, GFP_ATOMIC);
277	__skb_pull(skb, ETH_HLEN);
278	if (!nskb) {
279		DEV_STATS_INC(dev, tx_dropped);
280		return;
281	}
282
283	skb = nskb;
284	__skb_pull(skb, ETH_HLEN);
285	if (!is_broadcast_ether_addr(addr))
286		memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);
287
288	__br_forward(p, skb, local_orig);
289}
290
291/* called with rcu_read_lock */
292void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
293			struct sk_buff *skb,
294			struct net_bridge_mcast *brmctx,
295			bool local_rcv, bool local_orig)
296{
297	enum skb_drop_reason reason = SKB_DROP_REASON_NO_TX_TARGET;
298	struct net_bridge_port *prev = NULL;
299	struct net_bridge_port_group *p;
300	bool allow_mode_include = true;
301	struct hlist_node *rp;
302
303	rp = br_multicast_get_first_rport_node(brmctx, skb);
304
305	if (mdst) {
306		p = rcu_dereference(mdst->ports);
307		if (br_multicast_should_handle_mode(brmctx, mdst->addr.proto) &&
308		    br_multicast_is_star_g(&mdst->addr))
309			allow_mode_include = false;
310	} else {
311		p = NULL;
312		br_tc_skb_miss_set(skb, true);
313	}
314
315	while (p || rp) {
316		struct net_bridge_port *port, *lport, *rport;
317
318		lport = p ? p->key.port : NULL;
319		rport = br_multicast_rport_from_node_skb(rp, skb);
320
321		if ((unsigned long)lport > (unsigned long)rport) {
322			port = lport;
323
324			if (port->flags & BR_MULTICAST_TO_UNICAST) {
325				maybe_deliver_addr(lport, skb, p->eth_addr,
326						   local_orig);
327				goto delivered;
328			}
329			if ((!allow_mode_include &&
330			     p->filter_mode == MCAST_INCLUDE) ||
331			    (p->flags & MDB_PG_FLAGS_BLOCKED))
332				goto delivered;
333		} else {
334			port = rport;
335		}
336
337		prev = maybe_deliver(prev, port, skb, local_orig);
338		if (IS_ERR(prev)) {
339			reason = PTR_ERR(prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
340				 SKB_DROP_REASON_NOT_SPECIFIED;
341			goto out;
342		}
343delivered:
344		if ((unsigned long)lport >= (unsigned long)port)
345			p = rcu_dereference(p->next);
346		if ((unsigned long)rport >= (unsigned long)port)
347			rp = rcu_dereference(hlist_next_rcu(rp));
348	}
349
350	if (!prev)
351		goto out;
352
353	if (local_rcv)
354		deliver_clone(prev, skb, local_orig);
355	else
356		__br_forward(prev, skb, local_orig);
357	return;
358
359out:
360	if (!local_rcv)
361		kfree_skb_reason(skb, reason);
362}
363#endif